Skeletal Muscle Mass and Circumference Discrepancies Between Injured and Un-Injured Limbs Post-ACL Reconstruction

Abstract

Lower extremity injuries are common in sport. Anterior cruciate ligament (ACL) injuries often result in muscle atrophy in the thigh and calf muscles of the injured leg. Evaluating muscle atrophy via circumferences to document asymmetry has been recommended and is often used clinically (1). Previous studies have shown a small loss of skeletal muscle mass (SMM) may cause a greater loss in muscular strength (1), thus investigating muscle mass and girth may be beneficial in evaluating return to play post-ACL injury. PURPOSE: The purpose of this study was to examine SMM and circumference discrepancies between injured and uninjured limbs post- ACL reconstruction. METHODS: Participants (n = 7, 4 F, 3 M; 21.9 ± 4.3 y; 5.24 ± 4.74 y post injury) were tested using bioelectrical impedance analysis (BIA). Fat mass, fat-free mass, body fat percentage, and SMM (kg) for extremities and torso were obtained. Circumference measurements were taken on the injured (I) and un-injured (NI) limbs at the mid-patella, and superiorly and inferiorly of the patellar poles at 10, 15, and 20 centimeters, using a standard, non-elastic tape measure. RESULTS: There was no significant difference between SMM (I :14.54 ± 3.80 kg; NI:14.48 ± 3.48 kg; t(6) = 0.46, p = .660). Roughly half of participants had greater SMM in the injured leg versus un-injured leg. There were no significant differences in circumference measurements between the limbs. CONCLUSIONS: There was evidence of decreased SMM in some participants following ACL injury. It is possible that continued study with more participants may find difference in muscle mass following injury. SMM and circumferences provide useful information concerning muscular atrophy and discrepancies between limbs. SMM obtained via BIA may be utilized as a cost-effective measure indicative of knee stability and limb strength for return to play protocol (1). Future research should include measurements made pre and post injury/surgery to understand muscle mass progression following injury. 1-Ross, C. M., & Worrell, T. W. (1998). Thigh and calf girth following knee injury and surgery. Journal of Orthopaedic & Sports Physical Therapy, 27(1), 9-15.